Bumper beam having face with supported angled wall

ABSTRACT

A vehicle bumper beam includes front, rear, top and bottom walls and a reinforcement wall that define upper and lower tubes. The front wall includes a vertical section, an angled section, and a bent section. The reinforcement wall supports the angled section below the bent section to provide predictable and desired energy absorption. The angled section preferably includes an angled portion defining a first vertical dimension in the first tube and the vertical section defining a second vertical dimension, with a ratio of the first and second being about 1:3. Also preferably, the front wall is at least about 3 mm and the remaining walls are less than about 2.0 mm thickness, or more preferably the exterior ones of the remaining walls are less than about 1.7 mm. In one embodiment, the upper and lower tubes are spaced apart.

CROSS-REFERENCE TO RELATED APPLICATIONS

This application claims benefit of provisional application Ser. No.60/496,199, filed Aug. 19, 2003, entitled BUMPER BEAM HAVING FACE WITHSUPPORTED ANGLED WALL.

BACKGROUND

The present invention relates to vehicle bumper beams, and moreparticularly relates to a tubular beam constructed that is shaped forimproved energy absorption and predictable collapse.

Extruded and tubular bumper beams for modern passenger vehicles areknown, including ones made from aluminum. However, extruding processesand materials often require thick sections to obtain the strengthsrequired. Improvements are desired to decrease weight while maintainingenergy absorption. Further, improvements are desired to improve aconsistency and predictability of energy absorption upon collapse. Stillfurther, optimization of particular beam shapes is desired to facilitatemanufacture, while accomplishing the above objectives.

Thus, a bumper system having the aforementioned advantages and solvingthe aforementioned problems is desired.

SUMMARY OF THE PRESENT INVENTION

In one aspect, a bumper beam for a passenger vehicle includes a crosssection having an impact-receiving front wall, a rear wall, and paralleltop and bottom walls combining to define an exterior tube. An innerreinforcement wall extends between the front and rear walls andsubdivides the exterior tube into upper and lower tubular halves. Thefront wall includes a vertical section that extends parallel the rearwall and further includes an angled section connected by a bent sectionto the vertical section. The reinforcement wall extends parallel the topand bottom walls and is connected to and supports the angled section ata location spaced from the bent section. By this arrangement, thereinforcement wall combines with the vertical and angled sections of thefront wall and with the other walls to provide predictable and desiredenergy absorption upon impact.

In a narrower aspect, the angled section includes an angled portionlocated in the upper tubular half, and the angled portion defines afirst vertical dimension and the vertical section of the front walldefines a second vertical dimension, with a ratio of the first andsecond being about 1:3.

In another narrower aspect, the front wall is at least about 3 mm andthe remaining walls are less than about 2.0 mm thickness, or morepreferably the exterior ones of the remaining walls are less than about1.7 mm.

In another aspect, a bumper beam for a passenger vehicle includes across section having front and rear walls, and parallel top and bottomwalls combining to define an exterior tube. The front wall includes anup flange with a free end extending upward above the top wall forincreased stiffening of the front wall and the cross section.

In still another aspect, a bumper beam for a passenger vehicle includesa cross section with walls forming upper and lower tubes. The upper tubeis formed by first top and bottom walls and by first front and rearwalls, and the lower tube is formed by second top and bottom walls andby second front and rear walls. At least one of the first and secondfront walls includes an angled portion and a vertical portion connectedby a bent portion, with the vertical portion being greater in lengththan the angled portion; and with the other of the first and secondfront walls being entirely at an angle and not including a verticalportion.

In yet another aspect, a bumper beam for a passenger vehicle includes across section having front, top, rear, and bottom walls forming upperand lower tubes, and further has a reinforcement wall extending betweenthe front and rear walls. The front wall includes a vertical section, anangled section that extends at an acute angle to the vertical section,and a bent section connecting the vertical and angled sections, with thereinforcement wall being connected to the angled section at a locationspaced from the bent section.

These and other aspects, objects, and features of the present inventionwill be understood and appreciated by those skilled in the art uponstudying the following specification, claims, and appended drawings.

BRIEF DESCRIPTION OF DRAWINGS

FIG. 1 is a cross section of a tubular beam embodying the presentinvention;

FIG. 2 is a cross section illustrating an extruded tubular aluminum beamin prior art;

FIG. 3 is a graph showing a typical force versus deflection curve forthe beams of FIGS. 1 and 2;

FIG. 4 is an enlargement of FIG. 1; and

FIG. 5 is a cross section of a modified tubular beam embodying thepresent invention.

DETAILED DESCRIPTION OF PREFERRED EMBODIMENTS

For purposes of description herein, the terms “upper,” “lower,” “right,”“left,” “rear,” “front,” “vertical,” “horizontal,” and derivativesthereof shall relate to the invention as oriented in FIG. 1. However, itis to be understood that the invention may assume various alternativeorientations, except where expressly specified to the contrary. It isalso to be understood that the specific devices and processesillustrated in the attached drawings, and described in the followingspecification are simply exemplary embodiments of the inventive conceptsdefined in the appended claims. Hence, specific dimensions and otherphysical characteristics relating to the embodiments disclosed hereinare not to be considered as limiting, unless the claims expressly stateotherwise.

A vehicle bumper beam 10 (FIG. 1) includes front, rear, top and bottomwalls 11-14, and a reinforcement wall 15 that define upper and lowertubes. Notably, although the terms “front”, “rear”, “top”, and “bottom”are used for walls 11-14, it is contemplated that the beam can be usedin any orientation, with wall 11 being the object-engaging wall forfirst contact with an impacting object. Thus, for example, the term“front” is intended to refer to a front of the beam, and is not intendedto be unnecessarily limiting.

The front wall 11 includes a vertical section 16, an angled section 17,and a bent section 18. The reinforcement wall 15 supports the angledsection 17 below the bent section 18 to provide predictable and desiredenergy absorption. The angled section 17 is angled rearwardly at about20°. The angled section 17 preferably includes an angled portion 20defining a first vertical dimension 21 in the first tube and thevertical section 16 defining a second vertical dimension 22, with aratio of the first and second being about 1:3. Also preferably, thefront wall 11 is at least about 3 mm thickness and the remaining walls12-15 are less than about 2.0 mm thickness, or more preferably theexterior ones 12-14 of the remaining walls are less than about 1.7 mmand the reinforcement wall 15 being 1.9 mm. Radii at all 90° concavecorners are about 5 mm, but the radius at the concave corner of 70° isabout 2 mm. In one embodiment, the upper and lower tubes are spacedapart, as shown in FIG. 5, but it is noted that this second embodimentembodies some of the inventive aspects of the bumper beam 10, asdiscussed below. An up tab 23 provides additional front surface area andimproves beam strength, allowing the walls to be made thinner and thetube sections smaller. It is noted that the particular ratios of theillustrated beams of FIGS. 1 and 5 offer excellent beam strength andimpact energy-absorbing properties.

The beam 10 (FIG. 1) was developed to provide an increase of energyabsorption per kg of mass vs. conventional aluminum cross sectiondesigns (FIG. 2).

In particular, the cross section design utilizes theoretical mechanicsof materials and combines three distinct modes of energy management:transmission, system shape change and cross-sectional deformation. Theenergy absorption of beam 10 (FIG. 3) increases the efficiency of energyabsorption while decreasing the weight per unit length over knownconventional aluminum cross section designs. This increased efficiencyis obtained by incorporating the following unique designcharacteristics:

1) Impact Tab

FIG. 4 shows the impact tab (23) feature of the present increasedefficiency aluminum energy-absorbing cross section. This feature allowsfor an increase in the cross-sectional moment of inertia by increasingthe overall impact face while eliminating the weight burden associatedwith an overall larger cross section. This tab and its correspondingincrease in cross-sectional moment of inertia accounts for a portion ofthe increase stiffness and efficiency of the section design.

2) Impact Face Contour

FIG. 4 shows the impact face contour of the present increased efficiencyaluminum energy-absorbing cross section. This feature provides for anincrease in overall cross-sectional stiffness over the conventionalcross section designs by providing structural rigidity to the crosssection. The feature also provides for a controlled and predictablecross-sectional deformation by providing a deformation initiation point.

3) Impact Load Controlling Inner Structure

FIG. 4 shows the impact load controlling inner structure of the presentincreased efficiency aluminum energy-absorbing cross section. Theoptimization of position and thickness of this feature works inconjunction with feature 2 described above by providing tunable loadcarrying capabilities of the cross section design. Features 1 and 2allow for increased stiffness and efficiency up to the target loads atwhich point the optimized inner structure provides cross-sectionaldeformation to maintain these loads without exceeding an acceptablelevel. The impact face contour provides a point that initiates crush ofthe upper cavity. The vertical location of the impact controlling innerstructure will determine the load level at the onset of crush and willdefine the amount of crush the upper cavity will experience beforeloading of the lower cavity. When a defined amount of crush is designedinto the upper cavity, the lower cavity will maintain shape and provideoverall system rigidity during and after crush of the upper cavity.

MODIFICATION

The beam 10A (FIG. 5) is similar to the beam 10 (FIG. 1) in that thebeam 10A includes upper and lower tubes, a front wall with vertical andangled wall sections, and a reinforcement wall that connects to anangled portion of the angled wall below the bend. Beam 10A furtherincludes front and rear walls 25 and 26 that space the upper and lowertubes apart. The illustrated wall 25 is vertical and planar and spacedinwardly from the rear wall, and the wall 26 is “C” shaped.

It is to be understood that variations and modifications can be made onthe aforementioned structure without departing from the concepts of thepresent invention, and further it is to be understood that such conceptsare intended to be covered by the following claims unless these claimsby their language expressly state otherwise.

1. A bumper beam for a passenger vehicle comprising: a cross sectionincluding an impact-receiving front wall, a rear wall, and parallel topand bottom walls combining to define an exterior tube, and including aninner reinforcement wall extending between the front and rear walls thatsubdivides the exterior tube into upper and lower tubular halves; thefront wall including a vertical section that extends parallel the rearwall and including an angled section connected by a bent section to thevertical section; the reinforcement wall extending parallel the top andbottom walls and being connected to and supporting the angled section ata location spaced from the bent section, whereby the reinforcement wallcombines with the vertical and angled sections of the front wall andwith the other walls to provide predictable and desired energyabsorption upon impact.
 2. The bumper beam defined in claim 1, whereinthe angled section includes an angled portion located in the uppertubular half, the angled portion defining a first vertical dimension andthe vertical section of the front wall defining a second verticaldimension, a ratio of the first and second being about 1:3.
 3. Thebumper beam defined in claim 2, wherein the beam is constructed fromaluminum.
 4. The bumper beam defined in claim 3, wherein the beam isextruded.
 5. The bumper beam defined in claim 1, wherein the front wallis at least about 3 mm and the remaining walls are less than about 2.0mm thickness.
 6. The bumper beam defined in claim 5, wherein the top,rear and bottom walls are less than or equal to about 1.7 mm thickness.7. A bumper beam for a passenger vehicle comprising: a cross sectionincluding front and rear walls, and parallel top and bottom wallscombining to define an exterior tube, the front wall including an upflange with a free end extending upward above the top wall for increasedstiffening of the front wall and the cross section.
 8. The bumper beamdefined in claim 7, wherein the front wall includes a vertical sectionthat extends parallel the rear wall, and includes an angled sectionconnected by a bent section to the vertical section.
 9. The bumper beamdefined in claim 8, including an inner reinforcement wall extendingbetween the front and rear walls that subdivides the exterior tube intoupper and lower tubular halves; the reinforcement wall being connectedto and supporting the angled section at a location spaced from the bentsection, whereby the reinforcement wall combines with the vertical andangled sections of the front wall and with the flange to providepredictable and desired energy absorption upon impact.
 10. The bumperbeam defined in claim 9, wherein the beam is constructed from aluminum.11. The bumper beam defined in claim 10, wherein the beam is extruded.12. A bumper beam for a passenger vehicle comprising: a cross sectionincluding walls forming upper and lower tubes; the upper tube beingformed by first top and bottom walls and by first front and rear walls;the lower tube being formed by second top and bottom walls and by secondfront and rear walls; at least one of the first and second front wallsincluding an angled portion and a vertical portion connected by a bentportion, with the vertical portion being greater in length than theangled portion; the other of the first and second front walls beingentirely at an angle and not including a vertical portion.
 13. Thebumper beam defined in claim 12, wherein the first bottom wall and thesecond top wall are interconnected by front and rear connecting walls tothus define a third tube between the first and second tubes.
 14. Thebumper beam defined in claim 13, wherein the beam is constructed fromaluminum.
 15. The bumper beam defined in claim 14, wherein the beam isextruded.
 16. A bumper beam for a passenger vehicle comprising: a crosssection including front, top, rear, and bottom walls forming upper andlower tubes, and including a reinforcement wall extending between thefront and rear walls, the front wall including a vertical section, anangled section that extends at an acute angle to the vertical section,and a bent section connecting the vertical and angled sections, with thereinforcement wall being connected to the angled section at a locationspaced from the bent section.
 17. The bumper beam defined in claim 16,wherein the angled section includes an angled portion located in theupper tube, the angled portion defining a first vertical dimension andthe vertical section of the front wall defining a second verticaldimension, a ratio of the first and second being about 1:3.
 18. Thebumper beam defined in claim 16, wherein the beam is constructed fromaluminum.
 19. The bumper beam defined in claim 17, wherein the beam isextruded.
 20. The bumper beam defined in claim 16, wherein the frontwall is at least about 3 mm and the remaining walls are less than about2.0 mm thickness.
 21. The bumper beam defined in claim 20, wherein thetop, rear, and bottom walls are less than or equal to about 1.7 mmthickness.
 22. The bumper beam defined in claim 16, wherein the wallsare interconnected at joint locations, each of the joint locationsdefining a radius of at least about 5 mm on all surfaces that form a 90°angle or greater, and defining a radius of about 3 mm or less on allsurfaces that form less than a 90° angle.